This invention relates to automatic torque converter transmissions for motor vehicle applications. More particularly, it relates to automatic torque converter transmissions having means to selectively bypass the torque converter and, even more particularly, to a viscous coupling utilized in a torque converter bypass.
Torque converter type automatic transmissions have achieved almost universal application and acceptance in motor vehicles. While generally satisfactory in this application, torque converter automatic transmissions embody inherent slip and therefore incorporate inherent losses in vehicular fuel economy. In an effort to minimize this slippage and thereby optimize fuel economy, various efforts have been made to bypass the torque converter with some manner of direct drive which is typically brought into engagement when the vehicle is operating in the higher gear ratios and above a predetermined vehicular speed. While these direct drive bypass arrangements have resulted in improvements in fuel economy, they have also tended to engage rather abruptly. This abrupt engagement can be sensed in the passenger compartment of the motor vehicle, resulting in a derogation in the ride quality of the vehicle.